TWI790496B - Charging device, battery diagnosis system and charging method - Google Patents

Abstract

Embodiments of the present invention relate to a charging device, a battery diagnosis system, and a charging method. The problem to be solved by the present invention is to provide a charging device and a charging method in which information used for diagnosing the state of a battery pack can be easily obtained when charging the battery pack. According to the embodiment, the charging device charges a battery pack including one or more batteries and includes a controller. The controller superimposes the current waveform of a specific frequency on the reference current which is a direct current, and sets the superimposed superimposed current so that the direction in which the superimposed current flows continues to flow in the direction of the reference current over time consistent state. The controller controls the output current to the battery pack under the condition that the set overlapping current is output, and charges the battery pack by the output current.

Description

Charging device, battery diagnosis system and charging method

Embodiments of the present invention relate to a charging device, a battery diagnosis system, and a charging method.

In recent years, a battery pack including one or more batteries (secondary batteries) is mounted on equipment such as vehicles. In such machines, it is required that the battery pack be charged quickly in a short time. In addition, in equipment equipped with a battery pack, it is required to obtain the impedance characteristics of the battery pack, and to properly diagnose the state (deterioration state) of the battery pack based on the impedance characteristics and the like. In the diagnosis of the state of the battery pack including the calculation of the impedance characteristic of the battery pack, information measured by supplying current to the battery pack, etc. is used. In addition, information used for diagnosing the state of the battery pack is required to be easily obtained when the battery pack is being charged.

The problem to be solved by the present invention is to provide a charging device and a charging method in which information used for diagnosing the state of a battery pack can be easily obtained when charging the battery pack. Also, a battery diagnostic system including the charging device is provided. According to the embodiment, the charging device charges a battery pack including one or more batteries and includes a controller. The controller superimposes the current waveform of a specific frequency on the reference current which is a direct current, and sets the superimposed superimposed current so that the direction in which the superimposed current flows continues to flow in the direction of the reference current over time consistent state. The controller controls the output current to the battery pack under the condition that the set overlapping current is output, and charges the battery pack by the output current. According to the embodiment, a battery pack including one or more batteries is charged by a charging method. In the charging method, the current waveform of a specific frequency is superimposed on the reference current which is a direct current, and the superimposed superimposed current is set so that the direction in which the superimposed current flows continues to flow in the direction of the standard current over time. The state of the same direction. In the charging method, the output current to the battery pack is controlled in a state where the set overlapping current is output, and the battery pack is charged by the output current. According to the above-mentioned charging device and charging method, the information used for diagnosing the state of the battery pack can be easily obtained when the battery pack is being charged.

Hereinafter, embodiments will be described with reference to the drawings. (First Embodiment) Fig. 1 shows a battery diagnosis system 1 according to a first embodiment. As shown in FIG. 1 , the battery diagnosis system 1 includes a vehicle 2 as a machine, a charging device 3 , and a diagnosis server 5 . A battery pack 6 is mounted on the vehicle 2 . The battery pack 6 is charged by supplying electric power from the charging device 3 to the battery pack 6 . In addition, the charging device 3 and the diagnostic server 5 can exchange information with each other through wired or wireless. FIG. 2 shows the control system and communication system of the battery diagnosis system 1 . As shown in FIG. 2 , the battery pack 6 mounted on the vehicle 2 includes one or more batteries 7 . In the example shown in FIG. 2, a plurality of batteries 7 are electrically connected in series to the battery pack 6. Each of the one or more batteries 7 is a secondary battery such as a lithium ion battery. In addition, in a certain example, only one battery 7 may be provided in the battery pack 6 . In another example, a plurality of batteries 7 are electrically connected in parallel to the battery pack 6 . In another example, the battery pack 6 has both a series connection structure in which the plurality of batteries 7 are electrically connected in series and a parallel connection structure in which the plurality of batteries 7 are electrically connected. Also, in the vehicle 2 , an electrical contact A1 is formed, and in the charging device 3 , an electrical contact A2 is formed. In one example, the electrical contacts A1 and A2 are electrically connected to each other by connecting a power supply plug (not shown) of the charging device 3 to a power supply port (not shown) of the vehicle 2 . As a result, electric power can be supplied from the charging device 3 to the battery pack 6 (one or more batteries 7 ) of the vehicle 2 , and the battery pack 6 can be charged. The charging device 3 includes a power supply circuit 11 , a drive circuit 12 , a current detection circuit 13 , a voltage detection circuit 15 , a controller 20 and a communication circuit 30 . The drive circuit 12 includes a current generating circuit 17 and an output circuit 18 . The current generation circuit 17 includes a conversion circuit that converts the power supplied from the power supply circuit 11 into power output to the battery pack 6 when the battery pack 6 is charged. The current generating circuit 17 generates an output current for the battery pack 6 by converting the power output to the battery pack 6 , that is, generates a charging current for the battery pack 6 . The output circuit 18 outputs the electric power converted by the conversion circuit of the current generating circuit 17 to the battery pack 6 when the battery pack 6 is charged. As a result, the output current (charging current) generated by the current generating circuit 17 is supplied to the battery pack 6 . Also, the battery pack 6 is supplied with the output voltage from the output circuit 18 , which is the charging voltage of the battery pack 6 , in synchronization with the supply of the output current from the output circuit 18 . The current detection circuit 13 detects the output current (charging current of the battery pack 6 ) from the output circuit 18 . Also, the voltage detection circuit 15 detects the output voltage from the output circuit 18 (the charging voltage of the battery pack 6). The controller 20 constitutes, for example, a computer. The controller 20 is equipped with: a processor including a CPU (Central Processing Unit), an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array), or an integrated circuit (control circuit), and a memory, etc. memory media. The processor or integrated circuit provided in the controller 20 may be one or plural. The controller 20 performs processing by executing a program or the like stored in a storage medium or the like. The controller 20 includes a reference current setting unit 21 , a current waveform setting unit 22 , a current waveform superimposing unit 23 , an output current setting unit 25 , a current monitoring unit 27 and a voltage monitoring unit 28 . Each of the reference current setting unit 21, the current waveform setting unit 22, the current waveform superimposing unit 23, the output current setting unit 25, the current monitoring unit 27, and the voltage monitoring unit 28 is executed by the processor of the controller 20, etc. part of the processing. The reference current setting unit 21 sets a reference current that is a reference in relation to the output current from the output circuit 18 . The reference current setting part 21 is such that the reference current set by the reference current setting part 21 is a direct current. The direction in which the reference current flows is the same as the direction in which the current flows during charging of the battery pack 6 and the opposite direction to the direction in which the current flows during discharge from the battery pack 6 . The reference current setting unit 21 acquires a command current value, and sets a reference current (reference current locus) in a state where the current value of the reference current matches the command current value. Here, in a certain example, an operator or the like inputs an operation command related to charging on a user interface (not shown) of the vehicle 2 or the charging device 3 . Next, the reference current setting unit 21 obtains a command current value based on an operation command related to charging. In another example, the controller 20 acquires the type of the vehicle 2 on which the battery pack 6 to be charged is mounted. Next, the controller 20 selects a model corresponding to the type of vehicle with respect to the relationship of the output current (charging current) with respect to the elapsed time from the start of charging based on the data stored in the storage medium or the like. Next, the controller 20 sets the command current value based on the selected model, and the reference current setting unit 21 acquires the set command current value. The current waveform setting unit 22 is capable of acquiring a waveform setting command. The current waveform setting unit 22 sets the current waveform at the frequency (specific frequency) fa based on the acquisition of the waveform setting command. The current waveform is an alternating current that changes the direction of current flow every half cycle (1/2fa). In a certain example, a rectangular wave current of frequency fa is set as a current waveform. The current waveform superimposing unit 23 superimposes the current waveform set by the current waveform setting unit 22 and the reference current set by the reference current setting unit 21 based on the fact that the current waveform is set. Thereby, the superimposition current which superimposes the current waveform of frequency fa and a reference current is set. Next, the current waveform superimposing unit 23 transmits the set superimposed current (superimposed current trajectory) to the output current setting unit 25 . Here, in a certain example, the controller 20 obtains the timing for superimposing the current waveform and the reference current according to the operation command related to the charging input through the user interface mentioned above. Next, the controller 20 generates a waveform setting command when the current waveforms are superimposed, and the current waveform setting unit 22 acquires the generated waveform setting command. In another example, the controller 20 selects a model corresponding to the type of vehicle with respect to the timing at which the current waveform is superimposed on the reference current based on data stored in a storage medium or the like. Next, the controller 20 generates a waveform setting command at the timing of superimposing the current waveforms based on the selected model, and the current waveform setting unit 22 acquires the generated waveform setting command. Also, when the waveform setting instruction is not obtained by the current waveform setting section 22, that is, when it is not the timing to overlap the current waveform and the reference current, the current waveform setting section 22 does not set the current waveform. The current waveform superimposing unit 23 does not superimpose the current waveform on the reference current. Therefore, the reference current set by the reference current setting unit 21 is transmitted to the output current setting unit 25 . Fig. 3 shows an example of the reference current (reference current trajectory) set by the reference current setting part 21, and Fig. 4 shows an example of the current waveform set by the current waveform setting part 22 for display. Fig. 5A shows the superimposed current (overlapped current track) in which the current waveform in Fig. 4 overlaps the reference current in Fig. 3 , and Fig. 5B shows an enlarged region B1 in Fig. 5A. In FIGS. 3 to 5B, the horizontal axis represents the time t based on the start of charging, and the vertical axis represents the current I. In FIGS. 3 to 5B, the direction in which the reference current flows is shown as the positive direction. In the example shown in FIG. 3 , the reference current setting unit 21 sets the reference current so that the current value (command current value) becomes the value Ia between the time ta and the time tb and is consistent over time. In addition, in the example shown in FIG. 4, the current waveform setting unit 22 sets a rectangular wave current with a frequency fa as the current waveform between the time ta and the time tb. Here, the amplitude Ib of the set current waveform is smaller than the current value (Ia) of the reference current between time ta and time tb. In a certain example, the current waveform setting unit 22 sets the amplitude Ib of the current waveform (rectangular wave current) to 5% or less of the current value Ia of the reference current. That is, the peak-to-peak value (2Ib) of the current waveform is set to be 10% or less of the current value Ia of the reference current. In the waveform setting command, information related to the amplitude of the current waveform is included. The current waveform setting unit 22 sets the amplitude of the current waveform based on information related to the acquired amplitude of the current waveform. Since the current waveform is set as described above, as shown in FIG. 5A and FIG. 5B, the superimposed current is set so that the direction in which the superimposed current flows continues to coincide with the direction in which the reference current flows over time. state. That is, when the current value of the current flowing in the direction in which the reference current flows is positive, and the current value of the current flowing in the direction opposite to the direction in which the reference current flows is negative, the current of the superimposed current The value is maintained at a value greater than zero (positive value) over time. Therefore, in one example of FIG. 5A and FIG. 5B , at any time point between time ta and time tb, the direction in which the superimposed current flows is consistent with the direction in which the reference current flows. In addition, in the superimposed current in Fig. 5A and Fig. 5B, it is set that "between the time ta and the time tb, centering on the value Ia, that is, between the upper limit (Ia+Ib) and the lower limit A current waveform (rectangular wave current) that periodically changes between values (Ia-Ib)". Moreover, the set current waveform changes periodically with 1/fa as a cycle. In addition, in the example of FIG. 3 to FIG. 5B , the current waveforms are superimposed in the region where the current value becomes constant over time among the reference currents, but the present invention is not limited thereto. In a certain example, current waveforms are superimposed on a region where the current value decreases with time in the reference current. Even in this case, similarly, the superimposed current is set such that the direction in which the superimposed current flows coincides with the direction in which the reference current flows over time. In addition, the amplitude of the current waveform (rectangular wave current) is set to be 5% or less of the current value of the reference current. The output current setting unit 25 sets the target current value (target locus) of the output current from the output circuit 18 to the battery pack 6 . Furthermore, the output current setting unit 25 controls the driving of the current generating circuit 17 and controls the output to the battery pack 6 in a state where the output current is output at the set target current value. Here, when the current waveform setting section 22 sets the current waveform by the waveform setting command, the output current setting section 25 outputs the superimposed current set by the current waveform superimposing section 23 from the output circuit 18 In the output state, the output current to the battery pack 6 is controlled. In this case, the track of the temporal change of the superimposed current becomes the target track of the temporal change of the output current. On the other hand, when the current waveform is not set by the current waveform setting unit 22 , the output current setting unit 25 receives the reference current set by the reference current setting unit 21 from the output circuit 18 In the output state, the output current to the battery pack 6 is controlled. In this case, the track of the temporal change of the reference current becomes the target track of the temporal change of the output current. The current monitoring unit 27 obtains the detection result of the current detection circuit 13 with respect to the output current from the output circuit 18 (the charging current of the battery pack 6 ). That is, the current monitoring unit 27 obtains the detected current value of the output current. The voltage monitoring unit 28 obtains the detection result of the voltage detection circuit 15 with respect to the output voltage (charging voltage) synchronized with the output current (charging current of the battery pack 6 ) from the output circuit 18 . That is, the voltage monitoring unit 28 obtains the detected voltage value of the output voltage. Furthermore, the output current setting unit 25 acquires the detected current value of the output current from the current monitoring unit 27 . Furthermore, the output current setting unit 25 compares the set target current value with the detected current value for the output current, and obtains the deviation between the target current value and the detected current value. Next, the output current setting unit 25 controls the driving of the current generating circuit 17 and controls the output current from the output circuit 18 in a state where the deviation is close to zero. That is, the output current setting unit 25 performs feedback control in relation to the output of the output current (charging current). For example, when the superimposed current in FIG. 5A and FIG. 5B is set, the output current setting unit 25 performs feedback control of the output current in a state where the output current is close to the set superimposed current. Also, when an overlapping current is set such that the amplitude of the current waveform becomes 5% or less with respect to the current value of the reference current, the output current setting unit 25 sets the current value between the current value of the output current and the current value of the reference current ( Feedback control is performed when the difference between command current value) falls below 5%. The current monitoring unit 27 detects a temporal change in the output current based on the obtained detected current value of the output current. By doing so, it is possible to acquire and measure the temporal change of the output current. Here, even if the output current is controlled in a state where the set superimposed current is output, in the output current actually output, except for the component of the current waveform of the frequency fa superimposed on the reference current, Furthermore, it may also contain high harmonic components and noise of the current waveform. Therefore, the time-dependent change of the output current may be different from the time-dependent change of the set overlapping current. In some cases, even if the overlapping current is set so that the rectangular wave of frequency fa overlaps with the reference current, a current waveform close to a triangular wave or a sawtooth wave may be obtained as a change in the output current over time. Measurement data of reference current superimposition. Here, components of frequencies (3fa, 5fa, etc.) that are odd multiples of frequency fa are examples of the harmonic components of the current waveform. Fig. 6A shows a theoretical model of the time-dependent change of the output voltage when the overlapping current in Fig. 5A and Fig. 5B is output as the output current, and Fig. 6B shows the theoretical model of the change of the output voltage over time. Region B2 of Figure 6A is enlarged for illustration. In FIGS. 6A and 6B , the horizontal axis represents the time t based on the start of charging, and the vertical axis represents the voltage V. In the theoretical model of the output voltage in Fig. 6A and Fig. 6B, a component of frequency fa corresponding to the current waveform (rectangular wave current) appears between time ta and time tb. Here, in the theoretical model in which the reference current in Fig. 3 that does not overlap the current waveform is output as the output current, the output voltage is like a function Va(t) between time ta and time tb generally change over time. In the theoretical model of the output voltage in Figure 6A and Figure 6B, since the component of the existing frequency fa appears in the system, there is a periodicity centered on the function Va(t) between the time ta and the time tb. The voltage waveform of ground change. Moreover, the voltage waveform between time ta and time tb changes periodically with 1/fa as a period. The voltage monitoring unit 28 detects a temporal change in the output voltage in synchronization with the output current based on the obtained detected voltage value of the output voltage. Thereby, it is possible to acquire and measure the temporal change of the output voltage. Here, even if the output current is controlled in a state where the set superimposed current is output, in fact, the measured output voltage is the same as the output current, except for the frequency corresponding to the current waveform. In addition to the component of fa, there may be components of higher harmonics of the component of frequency fa, noise, and the like. Therefore, the time-dependent change of the output voltage may be different from the time-dependent change in the theoretical model corresponding to the set overlapping current. In a certain situation, even if the control is performed in the state where the overlapping current in Fig. 5A and Fig. 5B is output, the difference with Fig. 6A and Fig. 6B may be obtained as a change in the output voltage over time. Measurement data with different theoretical models. Here, among the high harmonic components of the frequency fa, components of frequencies (3fa, 5fa, etc.) that are odd multiples of the frequency fa are exemplified. The current monitoring unit 27 outputs the information on the temporal change of the output current, such as the acquired measurement data on the temporal change of the output current, to the outside of the charging device 3 via the communication circuit 30 . In addition, the voltage monitoring unit 28 outputs information on the temporal change in the output voltage, such as measurement data related to the obtained temporal change in the output voltage, to the charging device 3 via the communication circuit 30 . external. Thereby, the information etc. which relate to each temporal change of an output current and an output voltage are sent to the external computer etc. of the charging apparatus 3. As shown in FIG. In addition, the controller 20 may also store the information related to the temporal changes of the output current and the output voltage in a memory medium instead of outputting the information to the outside of the charging device 3, or in addition to outputting the information to the external charging device 3. In addition to the outside of the charging device 3, it is further stored in a storage medium or the like. At this time, the aforementioned information may also be temporarily memorized in a memory medium or the like. FIG. 7 shows the processing related to the charging of the battery pack 6 performed by the controller 20 . In the processing shown in FIG. 7, the controller 20 judges whether or not the charging command for the battery pack 6 is generated, that is, whether the charging command is ON (S101). In a certain example, the charging command is generated according to the aforementioned operation command input through the user interface. In another example, the charging command is generated based on the fact that the electrical contacts A1 and A2 are electrically connected to each other by connecting the power supply plug to the power supply port (not shown) of the vehicle 2 . When there is a charge command (S101-Yes), the reference current setting unit 21 acquires a command current value in relation to the output current (charging current) to the battery pack 6 (S102). Next, the reference current setting unit 21 sets the acquired command current value as the current value of the reference current to set the reference current ( S103 ). Next, the current waveform setting unit 22 judges whether the waveform setting command is generated, that is, whether the waveform setting command is ON (S104). The waveform setting command is generated in the same manner as any of the above-mentioned examples. When there is a waveform setting command (S104-Yes), the current waveform setting unit 22 acquires the waveform setting command, and sets the current waveform of frequency (specific frequency) fa according to the waveform setting command (S105). The amplitude and the like of the current waveform are set in the same manner as in any of the aforementioned examples. Next, the current waveform superimposing unit 23 superimposes the current waveform set in S105 and the reference current set in S103 (S106). Thereby, the superimposition current which superimposes the current waveform of frequency fa and a reference current is set. The superimposed current is set such that the direction in which the superimposed current flows coincides with the direction in which the reference current flows over time. Next, the output current setting unit 25 controls the driving of the current generating circuit 17 and controls the output from the output circuit 18 to the battery pack 6 in a state where the set superimposed current is output (S107). That is, the output current is controlled in a state where the set superimposed current is output. On the other hand, when the waveform setting command is not generated (S104-No), the output current setting unit 25 controls the drive of the current generating circuit 17 under the condition that the reference current set in S103 is output, and controls the slave The output of the output circuit 18 to the battery pack 6 (S108). That is, the output current is controlled in a state where the set reference current is output. Next, in the state of performing the output control in S107 or S108, the current monitoring unit 27 obtains the detected current value of the output current, and the voltage monitoring unit 28 obtains the detected voltage value of the output voltage (S109). Next, the process proceeds to S101. Next, when there is a charging instruction (S101-Yes), the processing after S102 is performed again. Next, in the state where the output control in S107 or S108 is performed, the aforementioned feedback control based on the deviation between the target current value and the detected current value, etc. is performed. At this time, the output current setting unit 25 may perform feedback control in a state where the difference between the current value of the output current (detection current value) and the current value of the reference current (command current value) falls below 5%. . When the charging command is not generated in S101 (S101-No), the controller 20 (output current setting unit 25) stops the output from the output circuit 18 to the battery pack 6 (S110). As a result, charging of the battery pack 6 is stopped. As shown in FIG. 2 , the diagnosis server 5 includes a Fourier transformer 31 and a calculator 32 . Each of the Fourier converter 31 and the calculator 32 is equipped with "a processor including a CPU, ASIC, or FPGA, or an integrated circuit (calculation circuit)" and "a storage medium such as a memory", which will be described later. Calculus processing. Each of the Fourier converter 31 and the calculator 32 implements the processing performed by the diagnosis server 5, that is, the diagnosis related to the state (deterioration state) of the battery pack 6 (one or more batteries 7). part of the processing. FIG. 8 shows the processing performed by each of the Fourier transformer 31 and the arithmetic unit 32 . As shown in FIG. 8 , the Fourier converter 31 of the diagnostic server 5 obtains information Iα(t) related to the temporal change of the output current from the communication circuit 30 of the charging device 3 . In a certain example, the information Iα(t) is measurement data of a temporal change in the output current measured by the current monitoring unit 27 . Here, in the measurement data of the temporal change of the output current, the portion of the current waveform at the frequency fa, etc. is made to be the same or slightly the same as the current value of the reference current with respect to the current waveform centered on zero. The deviation of the size of the amount. Therefore, in another example, the above-mentioned measurement data is corrected in accordance with the above-mentioned deviation in the portion of the current waveform at the frequency fa. Next, data on which the above-mentioned correction has been performed from the measurement data is obtained as information Iα(t) in the Fourier transformer 31 . Next, the Fourier transformer 31 performs Fourier transformation on the information Iα(t) (S121). By doing this, a spectrum Iβ(f) of the output current is generated, and the frequency characteristic of the output current is calculated. Here, f is a variable indicating frequency. Spectrum Iβ(f) includes components of frequency (specific frequency) fa and components of one or more frequencies that are integer multiples of frequency fa. In a certain example, the frequency spectrum Iβ(f) of the output current includes components of the frequency fa and components of frequencies that are odd multiples of the frequency fa (3fa, 5fa, etc.). Furthermore, the Fourier converter 31 obtains information Vα(t) related to the temporal change of the output voltage from the communication circuit 30 of the charging device 3 . In a certain example, the information Vα(t) is measurement data of a temporal change in the output voltage measured by the voltage monitoring unit 28 . Also, in another example, the measurement data of the output current is corrected to the information Iα(t) as described above, and the above measurement data of the output voltage is corrected correspondingly to the correction of the information Iα(t). . Next, data on which the above-mentioned correction has been performed from the measurement data is obtained as information Vα(t) in the Fourier transformer 31 . Next, the Fourier transform 31 performs Fourier transform on the information Vα(t) (S122). By doing so, a frequency spectrum Vβ(f) for the output voltage is generated, and the frequency characteristic of the output voltage is calculated. Spectrum Vβ(f) includes components of frequency (specific frequency) fa and components of one or more frequencies that are integer multiples of frequency fa. In a certain example, the frequency spectrum Vβ(f) of the output voltage includes a component of the frequency fa and a component of an odd multiple of the frequency fa (3fa, 5fa, etc.). Next, the calculator 32 acquires the spectrum Iβ(f) of the output current and the spectrum Vβ(f) of the output voltage, and performs calculations using the spectrum Iβ(f) and Vβ(f) (S123). In the calculation in S123, the autocorrelation function Corr(I, I) of the information Iα(t) related to the temporal change of the output current is calculated from the frequency spectrum Iβ(f). Next, from the spectrum Iβ(f) and Vβ(f), the relationship between the information Iα(t) related to the temporal change of the output current and the information Vα(t) related to the temporal change of the output voltage is calculated. The cross-correlation function Corr(I, V). Next, the calculator 32 performs calculations using the calculated autocorrelation function Corr(I, I) and cross-correlation function Corr(I, V) (S124). By the calculation of S124, the impedance characteristic of the battery pack 6 (one or more batteries 7) is calculated. In a certain example, by dividing the cross-correlation function Corr(I, V) by the auto-correlation function Corr(I, I), the components contained in the spectrum Iβ(f), Vβ(f) (spectral component ) to calculate the impedance for each of the frequencies. The diagnosis server 5 diagnoses the state (deterioration state) of the battery pack 6 based on the calculated impedance characteristics. In addition, when the measured data of the output current is used as information Iα(t), the information Iα(t) that deviates from the current waveform centered on zero, such as the portion of the current waveform at frequency fa, is is Fourier transformed. In this case, the data of the frequency spectrum Iβ(f) obtained by Fourier transform is corrected corresponding to the aforementioned deviation of the portion of the current waveform at the frequency fa. Next, the impedance characteristic is calculated using the data obtained by performing the above-mentioned correction from the data of the spectrum Iβ(f). Also, when using the measurement data of the output voltage as information Vα(t) and obtaining the frequency spectrum Vβ(f) by Fourier transform, it is the same as using the measurement data of the output current as information Iα(t). In the same way, appropriate corrections are made to the data of the spectrum Vβ(f). Next, the impedance characteristic is calculated using the above-mentioned corrected data from the data of the frequency spectrum Vβ(f). As described above, in this embodiment, the impedance characteristics of the battery pack 6 are calculated from the information Iα(t) and Vα(t) in the same way as the so-called rectangular wave impedance method. Here, the diagnosis of the state of the battery (battery pack) based on the rectangular wave impedance method and impedance characteristics is disclosed in Reference 1 (Japanese Patent Laid-Open No. 2014-126532) and Reference 2 (Electrochimica Acta vol .246 (2017) p.800‐p.811). In this embodiment, the output current to the battery pack 6 is controlled. Therefore, in the calculation of the impedance characteristic, the autocorrelation function Corr(I, I) of the information Iα(t) related to the temporal change of the output current is used. As described above, in the present embodiment, the superimposed current obtained by superimposing the current waveform (rectangular wave current) of the frequency fa on the reference current which is direct current is set by the current waveform superimposing unit 23 . Next, the output current setting unit 25 controls the output current to the battery pack 6 in a state where the set superimposed current is output, and charges the battery pack 6 by the output current. By controlling the output current as described above, the measurement data of the temporal change of the output current and the measurement data of the temporal change of the output voltage synchronized with the output current can be used in the battery pack 6 In the diagnosis of the state of the battery pack 6 such as the calculation of the impedance characteristic. Therefore, the information used for diagnosing the state of the battery pack 6 can be easily obtained when the battery pack 6 is being charged. In addition, in the present embodiment, the current waveform superimposing unit 23 sets the superimposed current in a state where the direction in which the superimposed current flows coincides with the direction in which the reference current flows over time. Therefore, even when the output current is controlled in a state where the overlapping current is output, the output current can be continuously supplied to the battery pack 6 over time, and the battery pack 6 can be continuously charged over time. As a result, the battery pack 6 is properly charged. Also, in the present embodiment, the current waveform setting unit 22 sets the amplitude of the current waveform to be 5% or less with respect to the current value of the reference current. Therefore, by controlling the output current in a state where the overlapping current is output, the deviation between the current value of the output current and the current value of the reference current (command current value during charging) is reduced. Thus, the battery pack 6 is caused to be more properly charged. In addition, in the present embodiment, the output current setting unit 25 performs feedback control on the output current in a state where the deviation between the target current value and the detected current value is close to zero. For example, when an overlapping current is set such that the amplitude of the current waveform becomes 5% or less with respect to the current value of the reference current, the output current setting unit 25 sets the current value of the output current (detection current value) to the reference current. Feedback control is performed when the difference between current values (command current values during charging) falls below 5%. As a result, the deviation between the current value of the output current and the current value of the reference current (command current value during charging) is further reduced, enabling the battery pack 6 to be charged more appropriately. Also, in the present embodiment, when the waveform setting command is not generated, etc., the current waveform is not set, and the output current setting part 25 controls the output current to the battery pack 6 in a state where the set reference current is output. the output current. Therefore, the control model related to the output current to the battery pack 6 can be selected according to the situation such as whether or not it is necessary to obtain information used for diagnosis of the battery pack 6 . In addition, in this embodiment, the diagnosis server 5 calculates the impedance characteristic of the battery pack 6 as described above based on the measurement data of the temporal change of the output current and the measurement data of the temporal change of the output voltage. . Therefore, the impedance characteristics are appropriately calculated using the measurement data, and the state of the battery pack 6 is appropriately diagnosed. (Modification) In a modification, the current waveform setting unit 22 further sets current waveforms at frequencies that are one or more integral multiples of the frequency fa in addition to the current waveform at the frequency (specific frequency) fa. Next, the current waveform superimposing unit 23 superimposes the current waveform of one or more frequencies that are an integral multiple of the frequency fa on the reference current in addition to the current waveform of the frequency fa to set the superimposed current. In this modified example as well, the output current setting unit 25 controls the output current to the battery pack 6 in a state where the set superimposed current is output. In this modified example, superimposed current output control is performed to superimpose current waveforms of one or more frequencies that are an integral multiple of the frequency fa in addition to the current waveform of the frequency fa. Therefore, by calculating the spectrum Iβ(f) of the output current and the spectrum Vβ(f) of the output voltage as in the aforementioned embodiment, it becomes possible to obtain Components (spectral components) are acquired at more frequencies among frequencies that are integer multiples of the frequency fa. Thereby, the impedance is calculated at more frequencies among the frequencies that are integer multiples of the frequency fa, and the state (deteriorated state) of the battery pack 6 can be diagnosed more appropriately. In a certain example, in addition to the current waveform of frequency (first frequency) fa, the current waveforms of frequencies fb and fc (fc>fb) which are two integral multiples of frequency fa are set to overlap the reference current the overlapping current. Next, the output current to the battery pack 6 is controlled in a state where the set overlapping current is output. In this case, frequency (second frequency) fb is preferably an even multiple of frequency fa, for example, frequency 2fa. Next, the frequency (third frequency) fc is preferably an even-number multiple of the frequency fa and an even-number multiple of the frequency fb, for example, frequency 4fa (=2fb). By setting the frequencies fa to fc as described above, each of frequencies that are odd multiples of frequency fa is related to frequency fb, frequencies that are odd multiples of frequency fb, frequency fc, and frequencies that are odd multiples of frequency fc Any frequency of is different. Thereby, in each of the frequency spectra Iβ(f) and Vβ(f) calculated as in the above-mentioned embodiment, more frequencies can be obtained at frequencies that are integer multiples of the frequency fa Element. Thereby, the impedance is calculated at more frequencies among the frequencies that are integer multiples of the frequency fa, and the state (deteriorated state) of the battery pack 6 can be diagnosed more appropriately. In addition, in a certain modified example, the Fourier converter 31 and the calculator 32 may be mounted on the charging device 3 . In this modified example, the frequency characteristics of the output current and the frequency characteristics of the output voltage are calculated by the charging device 3, and the impedance characteristics of the battery pack 6 are calculated. Also, in another modified example, one of the Fourier converter 31 and the calculator 32 may be mounted on the charging device 3 . Moreover, the aforementioned control of the output current (charging current) of the charging pack 6 is applicable not only to charging the battery pack 6 of the vehicle 2 but also to charging the battery packs of devices other than the vehicle 2 . According to at least one of these embodiments or examples, the charging device and the charging method superimpose a current waveform of a specific frequency on a reference current that is a direct current, and the superimposed superimposed current is set. A state in which the direction in which the superimposed current flows is continuously consistent with the direction in which the reference current flows is maintained over time. Then, in the state where the set overlapping current is output, the output current to the battery pack is controlled, and the battery pack is charged by the output current. Thereby, it is possible to provide a charging device and a charging method in which information used for diagnosing the state of the battery pack can be easily obtained when charging the battery pack. Although several embodiments of the present invention have been described, these embodiments are disclosed as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in other various forms, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments or modifications thereof are included in the scope or gist of the invention, and are also included in the invention described in the claims and its equivalent scope.

1: Battery diagnostic system 2: Vehicle 3: Charging device 5:Diagnostic server 6: Battery pack 7: battery A1: electrical contacts A2: electrical contacts 11: Power circuit 12: Drive circuit 13: Current detection circuit 15: Voltage detection circuit 20: Controller 30: Communication circuit 17: Current generating circuit 18: Output circuit 21: Reference current setting part 22: Current waveform setting part 23: Current waveform overlapping part 25: Output current setting part 27: Current Monitoring Department 28: Voltage Monitoring Department 31: Fourier Transformer 32: Calculator

[FIG. 1] is a schematic diagram showing the battery diagnosis system of the first embodiment. [Fig. 2] is a block diagram schematically showing the control system and communication system of the battery diagnosis system in Fig. 1. [FIG. 3] is a schematic diagram showing an example of the reference current set by the controller of the charging device according to the first embodiment. [FIG. 4] is a schematic diagram showing an example of the current waveform set by the controller of the charging device according to the first embodiment. [FIG. 5A] is a schematic diagram showing an overlapping current in which the current waveform in FIG. 4 and the reference current in FIG. 3 are superimposed. [FIG. 5B] is a schematic diagram showing enlarged area B1 in FIG. 5A. [Fig. 6A] shows the temporal characteristics of the output voltage when the superimposed current in Fig. 5A and Fig. 5B is output as the output current to the battery pack in the charging device of the first embodiment A schematic diagram showing the theoretical model of change. [FIG. 6B] is a schematic diagram showing enlarged area B2 in FIG. 6A. [FIG. 7] is a flow chart showing the processing related to the charging of the battery pack performed by the controller of the charging device according to the first embodiment. [FIG. 8] is a schematic diagram showing the processing performed by each of the Fourier converter and the arithmetic unit of the diagnosis server according to the first embodiment.

1: Battery diagnostic system

2: Vehicle

3: Charging device

5:Diagnostic server

6: Battery pack

7: battery

11: Power circuit

12: Drive circuit

13: Current detection circuit

15: Voltage detection circuit

17: Current generating circuit

18: Output circuit

20: Controller

21: Reference current setting part

22: Current waveform setting part

23: Current waveform overlapping part

25: Output current setting part

27: Current Monitoring Department

28: Voltage Monitoring Department

30: Communication circuit

31: Fourier Transformer

32: Calculator

A1, A2: electrical contacts

Claims (8)

A charging device for charging a battery pack having one or more batteries, the charging device is provided with: a controller that superimposes a current waveform of a specific frequency on a reference current that is a direct current, and performs The superimposed superimposed current is set so that the direction in which the superimposed current flows continues to coincide with the direction in which the reference current flows over time, and the control for the superimposed superimposed current is output in the state where the superimposed current is set. The output current of the battery pack is used to charge the battery pack by the output current. The controller measures and obtains the change of the output current over time, and is applied to the battery pack synchronously with the supply of the output current. The temporal change of the output voltage of the aforementioned battery pack. The charging device according to claim 1, wherein the controller sets the rectangular wave current of the specific frequency as the current waveform superimposed on the reference current. The charging device according to claim 1, wherein the controller sets the amplitude of the current waveform superimposed on the reference current to be 5% or less relative to the current value of the reference current. The charging device as described in claim 1, wherein the controller, in addition to the current waveform of the specific frequency, further overlaps the current waveform with a frequency of one or more integral multiples of the specific frequency with the reference current , to set the aforementioned overlapping current. The charging device as described in claim 1, wherein, the former The controller stores at least one of the information related to the temporal change of the output current and the information related to the temporal change of the output voltage and outputs to the outside. A battery diagnosis system comprising: a charging device as described in claim 1, and a Fourier converter for the aforementioned output current by Fourier transforming information related to the temporal change of the aforementioned output current , to calculate the frequency characteristics including the above-mentioned specific frequency component and the above-mentioned specific frequency component or more than one frequency component of an integer multiple of the above-mentioned frequency, and by the time-dependent The changing information is Fourier transformed, and for the aforementioned output voltage, the frequency characteristics including the aforementioned specific frequency components and the frequency components of more than one integer multiple of the aforementioned specific frequency are calculated, and the calculator is based on the aforementioned output The aforementioned frequency characteristics of the current and the aforementioned frequency characteristics of the aforementioned output voltage synchronous with the aforementioned output current are used to calculate the impedance characteristics of the aforementioned battery pack. The battery diagnosis system as described in claim 6, wherein at least one of the aforementioned Fourier converter and the aforementioned calculator is mounted on the aforementioned charging device. A charging method for charging a battery pack having one or more cells, the charging method comprising the steps of: superimposing a current waveform of a specific frequency on a reference current which is a direct current, and superimposing the superimposed The overlapping current is set so that the direction in which the aforementioned overlapping current flows continues with time The step of controlling the output current to the aforementioned battery pack in the state where the direction of the reference current flowing is consistent, and charging the aforementioned battery pack by the aforementioned output current in the state where the set overlapping current is output and a step of measuring and acquiring a temporal change of the output current and a temporal change of an output voltage applied to the battery pack in synchronization with supply of the output current.

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